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Error debugging on fresh phoenix 1.8 project #6403
Description
Environment
- Elixir version (elixir -v): 1.18.4
- Phoenix version (mix deps): 1.8.0
- Operating system: Linux 6.16.0-5-cachyos
Actual behavior
Starting the debugger with Elixir LS on a fresh phoenix app, when typing localhost:4000, the following appears in the debug console
warning: a Mix listener expected by Phoenix.CodeReloader is missing.
Please add the listener to your mix.exs configuration, like so:
def project do
[
...,
listeners: [Phoenix.CodeReloader]
]
end
(debugger 6.0.2) dbg_debugged.erl:95: :dbg_debugged.reply/1
(debugger 6.0.2) dbg_debugged.erl:89: :dbg_debugged.handle_command/1
(debugger 6.0.2) dbg_debugged.erl:77: :dbg_debugged.msg_loop/2
(mix 1.18.4) lib/mix/sync/lock.ex:112: Mix.Sync.Lock.with_lock/3
(debugger 6.0.2) dbg_debugged.erl:95: :dbg_debugged.reply/1
(debugger 6.0.2) dbg_debugged.erl:89: :dbg_debugged.handle_command/1
(debugger 6.0.2) dbg_debugged.erl:77: :dbg_debugged.msg_loop/2
(stdlib 7.0.2) gen_server.erl:2470: :gen_server.try_handle_call/4
(stdlib 7.0.2) gen_server.erl:2499: :gen_server.handle_msg/3
(stdlib 7.0.2) proc_lib.erl:333: :proc_lib.init_p_do_apply/3Expected behavior
It should run the debugger without any errors
Activity
josevalim commentedon Aug 10, 2025
cc @lukaszsamson
markquezada commentedon Aug 12, 2025
@josevalim FYI, we are also seeing this error after upgrading to 1.8
Elixir version (elixir -v): 1.18.1
Phoenix version (mix deps): 1.8.0
Operating system: mac os sonoma
lukaszsamson commentedon Aug 12, 2025
Are you running with reloader turned on? It has known incompatibility with OTP debugger